1. Field of the Invention
This invention relates generally to heat exchange structures, and is particularly concerned with improvements in heat exchangers of the type disclosed in U.S. Pat. No. 5,501,270 issued Mar. 26, 1996 in the names of the present inventor and Barry W. Blumel.
2. Background Information
U.S. Pat. No. 5,501,270 shows a heat exchange structure that comprises a stack of metal fins laced together by parallel tubes. Consecutive fins are substantially uniformly spaced from each other throughout the stack. The fins comprise identical patterns of collared holes through which the tubes lace the stack. The tubes have oval transverse cross sections. In plan view, the fin holes have oval shapes just slightly larger than the oval cross sections of the tubes. The fins and tubes are brazed together around each hole through which a tube passes.
When the heat exchanger is in use, a first heat exchange fluid flows through the parallel tubes, and a second heat exchange fluid flows through the stack from a front face of the stack to a rear face of the stack. The second heat exchange fluid enters the front face from a direction that is generally perpendicular to the tubes.
Within the interior of the stack, a major portion of the area of each fin lies in a respective plane that is non-perpendicular to the direction from which the second fluid approaches it. In general, those interior portions of the fins are disposed in planes that are non-perpendicular to the direction from which the second fluid approaches the front face of the stack.
In addition to the collared holes, the interior portions of the fins contain rows of louvered slots arranged to cause the second fluid to flow through the slots as it passes through the stack. The novel core constructions disclosed in the referenced patent are efficient in respect of both heat exchange and fluid pressure drop.